Omnidirectional antenna for indoor and outdoor use

Abstract

A plate-shaped radiating element of a shape having at least three planes is formed by bending a metal plate having a substantially rectangular shape. A first slit is provided from a lower edge of the plate-shaped radiating element up to a portion in the vicinity of an upper edge of the plate-shaped radiating element while passing through a center point of the plate-shaped radiating element, and forms plate-shaped dipole elements on both sides thereof. A second slit is provided parallel to the upper edge of the plate-shaped radiating element and forms a folded element on an upper side thereof. Feeding points are provided on both sides of the first slit at the lower edge of the plate-shaped radiating element.

1. An antenna, comprising:
 a plate-shaped radiating element, formed by bending a metal plate having a substantially rectangular shape so as to have a shape having at least three planes each extending in a first direction between a first edge of the plate-shaped radiating element and a second edge of the plate-shaped radiating element, the plate shaped radiating element having a third edge and a fourth edge in the first direction; 
 a first slit, provided in the first direction between a portion in the vicinity of the first edge and a portion in the vicinity of the second edge through a center point of the plate-shaped radiating element, and forming plate-shaped dipole elements on both sides of the first slit; 
 a second slit, provided in a second direction perpendicular to the first direction, and forming a first folded element on a side of the first edge; 
 a third slit, provided in the second direction, and forming a second folded element on a side of the second edge; 
 a fourth slit, provided in a second direction between the third edge and a portion in the vicinity of the center point; 
 a fifth slit, provided in the second direction between the fourth edge and a portion in the vicinity of the center point; and 
 feeding points, provided between the first slit and the fourth slit, and between the first slit and the fifth slit, 
 wherein the fourth slit and the fifth slit divide the dipole elements into first dipole elements and second dipole elements, and 
 wherein the first and second dipole elements are greater in width in the first direction than the first and second folded elements. 
 
     
     
       2. An antenna unit incorporating the antenna as claimed in  claim 1 , further comprising:
 a cover adapted to cover the antenna. 
 
     
     
       3. The antenna unit as claimed in  claim 2 , further comprising:
 a base attachable to the cover. 
 
     
     
       4. The antenna unit as claimed in  claim 2 , further comprising:
 an output member, operable to output a signal based on electromagnetic waves received by the antenna. 
 
     
     
       5. The antenna unit as claimed in  claim 2 , further comprising:
 an outdoor setting-purpose attaching member which is attached to the cover. 
 
     
     
       6. The antenna unit as claimed in  claim 2 , further comprising:
 a supporting member, integrally or detachably provided with the cover, and selectively attachable to one of an indoor setting-purpose base and an outdoor setting-purpose attaching member. 
 
     
     
       7. The antenna unit as claimed in  claim 2 , wherein a top portion of the cover has an inclined shape. 
     
     
       8. The antenna unit as claimed in  claim 2 , wherein a length of the cover in the first direction is longer than a length of the cover in the second direction. 
     
     
       9. The antenna unit as claimed in  claim 2 , wherein
 the cover has a cylindrical shape, and 
 a longitudinal length of the cover is longer than a diametrical length of the cover on a side parallel to a polarization plane of electromagnetic waves received by the antenna. 
 
     
     
       10. The antenna as claimed in  claim 1 , wherein the plate-shaped radiating member is formed by bending the metal plate along a longer side of the metal plate. 
     
     
       11. An antenna, comprising:
 an antenna member comprising a plate-shaped radiating element which is formed by bending a metal plate having a substantially rectangular shape so as to have a shape having at least three planes, or a circular shape; and 
 a cover having a vertically-standing cylindrical shape and adapted to cover the antenna member, a vertical length of the cover being longer than a diametrical length of the cover; and 
 a supporting member, integrally or detachably provided with the cover, and selectively attachable to one of an indoor setting-purpose base and an outdoor setting-purpose attaching member, wherein: 
 two opposing edges of the plate-shaped radiating element are parallel to the vertical direction; 
 the antenna member is operable to receive horizontally polarized electromagnetic waves with omnidirectional characteristic in a horizontal plane and 
 the antenna member further comprising:
 a first slit, which forms plate-shaped dipple elements on both sides of the first slit, vertically provided from a portion between feeding points to a portion in the vicinity of a first edge of the plate-shaped dipole elements other than the two opposing edges; and 
 a second slit, which forms a folded element on a side of the first edge, horizontally provided along the first edge crossing an end of the first slit. 
 
 
     
     
       12. The antenna as claimed in  claim 11 , further comprising:
 an output member, operable to output a signal based on the electromagnetic waves received by the antenna member.